It saw an 84% year-on-year rise in summer sales of Costa Rica's currency, the colon.

Post Office Travel Money, which accounts for one in four of all UK currency transactions, said its sales of this currency are also up 46% this year so far compared with the same period in 2015.

Post Office also saw strong demand for the Brazilian real as sports enthusiasts headed off for the Olympics. Real sales rose 70% year-on-year over the summer period, making it the second strongest-growing currency for sales over the summer in the report. So far this year, sales of the Brazilian real are up by 41% compared with a year earlier.

Meanwhile, sales of Peru's nuevo sol are up by 19% for the year to date, compared with a year earlier. And sales of the Chilean peso have lifted by 23% during the year to date compared with the same period in 2015.

The pound has seen some strong fluctuations following the vote to leave the EU. Overall, as in 2015, the euro was Post Office's best-selling currency between June and August this year, followed by the US dollar.

Christopher Dewe, head of Post Office Travel Money, said: "Costa Rica is the latest Latin American destination to come within the orbit of adventurous holidaymakers.

"With gains for Brazil, Chile and Peru as well, there is little doubt that growing numbers of UK tourists are prepared to travel long distances for their holiday."